Steve Goldstein, the department’s under secretary for public diplomacy and public affairs, confirmed on Tuesday that Tillerson found out about his own firing from Trump’s tweet announcing it, and that Tillerson was “unaware of the reason” for his dismissal, which he had not discussed with Trump.

“The Secretary had every intention of staying because of the critical progress made in national security,” Goldstein said. “The secretary did not speak to the president and is unaware of the reason, but he is grateful for the opportunity to serve, and still believes strongly that public service is a noble calling.”

While the White House said Tillerson was informed on Friday of his imminent dismissal, the Associated Press reported on Tuesday that White House chief of staff John Kelly called Tillerson on Friday to inform him that a presidential tweet about him may be coming but did not give any more details.

Trump told reporters on the White House lawn on Tuesday morning that he did not discuss his decision with Tillerson but that the two “have been talking about this a long time.”

“I didn’t discuss it very much with him,” Trump said. “I made that decision by myself.”

The president said that while he personally likes Tillerson and got along with him, the two disagreed on important policy issues, including the Iran nuclear deal, and had “different mindsets.”

“I think Rex will be much happier now, but I really appreciate his service,” Trump said.

On Tuesday afternoon, the White House named Heather Nauert, the department’s spokesperson and a former Fox News host, acting under secretary to replace Goldstein. Even with Nauert in her new role – the fourth-most senior in the department – seven of the nine top posts remain unfilled.

“This has been an honour of a lifetime and I’m grateful to the secretary and the President for this opportunity,” Goldstein said in statement to CNN. “I wish everyone well and look forward to getting more rest and perhaps winning an indoor rowing competition. We will see what happens next.”

Trump selected CIA Director Mike Pompeo to replace Tillerson. The CIA’s deputy director, Gina Haspel, will succeed Pompeo, becoming the first woman to lead the agency pending Senate confirmation for both her and Pompeo.

Trump’s frayed relationship with Tillerson has been well-documented. The president frequently complained to his West Wing advisers about Tillerson, and Tillerson once reportedly called Trump a “moron” behind his back.